This study is aimed at identifying how the burden of care of the elderly patients suffering from dementia and physical disabilities is related to mental health and subjective well-being of the family caregivers. In this study, survey research design was used and data were collected through convenient sampling from 100 caregivers of elderly patients with dementia (n = 50) and physical disability (n = 50). Four tools were used; The Caregiver Strain Index (Robinson & Price, 1982); General Health Questionnaire (Goldberg, 1978); and The Subjective Happiness Scale (Lyubomirsky and Lapper, 1999). Correlation and t-test were carried out and findings showed a significant negative correlation between burden of care and the caregiver’s quality of life. The caregivers of dementia patients showed a significant decline in their mental health as compared to the caregivers of patients with physical disability; however both the groups did not show any significant difference in terms of burden of care. Significant gender differences were noted in terms of depression. Further results indicated that the caregiver’s education and occupation were significant predictors of burden of care. The importance of the study lies in the fact that the findings will be highly valuable in gaining insight into the psychological problems experienced by the family caregivers in Pakistan.